Maybe you could make the animation by yourself or just don`t let the ducks get too near to the player (don`t place and let them walk into the gameplay area).

If you`ll buy it (I think it`s worth it): You should work with an LOD system for the ducks and/or reduce the texture size. A 1024x1024 texture and 1350 tris per duck (when placing ~10-15 ducks in the level plus some flying ravens and maybe one or two cocks) is a bit too much for us I think. Of course you could experiment around with it, but we should stay on the current performance level.